1. University of Michigan, Center for Healthcare Outcomes and Policy, and Center for Evaluating Health Reform, Ann Arbor, Michigan (K.H.S.)
2. Center for Healthcare Outcomes and Policy, Ann Arbor, Michigan (L.G.)
3. Center for Healthcare Outcomes and Policy, Center for Evaluating Health Reform, and University of Michigan School of Public Health, Ann Arbor, Michigan (A.M.R.)
4. University of Michigan and Center for Healthcare Outcomes and Policy, Ann Arbor, Michigan (S.A.W.).